Fix setxid race handling exiting threads

2 files changed, 15 insertions, 1 deletions

diff --git a/nptl/ChangeLog b/nptl/ChangeLog
index 06d19b9411..c44ce2af6f 100644
--- a/nptl/ChangeLog
+++ b/nptl/ChangeLog
@@ -1,3 +1,8 @@
+2011-08-31  Andreas Schwab  <schwab@redhat.com>
+
+	* allocatestack.c (setxid_mark_thread): Ensure that the exiting
+	thread is woken up.
+
 2011-08-20  David S. Miller  <davem@davemloft.net>
 
 	* Makefile (tst-cleanup0.out): Fix typo in output redirection.
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 9b8b0ceb40..23d2ce559c 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -999,7 +999,16 @@ setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
 
       /* If the thread is exiting right now, ignore it.  */
       if ((ch & EXITING_BITMASK) != 0)
-	return;
+	{
+	  /* Release the futex if there is no other setxid in
+	     progress.  */
+	  if ((ch & SETXID_BITMASK) == 0)
+	    {
+	      t->setxid_futex = 1;
+	      lll_futex_wake (&t->setxid_futex, 1, LLL_PRIVATE);
+	    }
+	  return;
+	}
     }
   while (atomic_compare_and_exchange_bool_acq (&t->cancelhandling,
 					       ch | SETXID_BITMASK, ch));